Background Research into retinal blinding diseases has attracted considerable efforts. Anti-VEGFA antibodies (ranibizumab or Lucentis and bevacizumab or Avastin ) have recently been introduced in the USA and Europe. Although these anti-angiogenic drugs are used successfully for the treatment of wet AMD, they do not address the disease causation. Similarly, other therapeutic interventions to date are palliative for the majority of retinal degenerative diseases. This highlights the need to better understand the etiology of retinal diseases and to inform new approaches for treatment. Results 1. Gene therapy for early congenital blindness (LCA) In collaboration with Peter Colosi's lab (NNRL), we have initiated gene therapy approaches using rd16 mice as a model system. Several methods are employed to accomplish gene delivery into the retina. One approach involves replacement of the defective gene (Cep290). These methods are being first tested by in vivo electroporation and will be followed by subretinal injection of AAV vectors carrying the DNA sequence of interest. 2. Derivation of photoreceptors from human embryonic stem cell (HESC) and Mller glia cell lines Our goal is to develop optimal conditions for photoreceptor differentiation and identify molecular markers for cells that can be used for transplantation. We are using human embryonic stem cells to generate committed photoreceptors and retinal interneurons in vitro. NIH-approved HESC lines were differentiated to retinal cells and transplanted into the subretinal space of young wild type mice to investigate their potential to integrate into the host retina. The adopted protocol reproducibly generated neurons expressing photoreceptor-specific markers after grafting. In future experiments differentiation of HESCs will be accomplished by transfection of recombinant BACmids engineered to express EGFP and tdTomato under control of endogenous photoreceptor gene regulatory elements. Furthermore, we are testing the hypothesis that by introducing NRL in vivo following retinal injury we will enable Mller glia cells to differentiate into rod photoreceptors. Preliminary results obtained by in vivo electroporation of NRL in adult mice were encouraging. More transgenic mice were generated as tools to further test this hypothesis.